The molecular revolution is beginning to have an impact on all aspects of tuberculosis. Work in diagnostics is expected to progress in maximizing genetic testing of mycobacteria. Drug development will benefit from recently acquired knowledge on molecular mechanisms of drug action. The availability of the complete genome of Mycobacterium tuberculosis, and better tools for genetic work with mycobacteria, will promote the development of vaccine candidates. Our work has contributed to the definition of the mechanisms of resistance to rifampin, fluoroquinolones, and ethambutol, and, using molecular analysis, to a better understanding of the epidemiology of mycobacterial infections. This overview of the direction of tuberculosis research today illustrates the impact of novel scientific approaches on the investigation of old problems.